Engine



Nov. 30, 1965 R. s. RAE 3,220,183

ENGINE Original Filed March 22, 1954 6 Sheets-Sheet 1 I l l RANDOLPHSAMUEL RA E,

IN VEN TOR.

ATTORNEK Nov. 30, 1965 Original Filed March 22, 1954 R. S. RAE

ENGINE 6 Sheets-Sheet 2 RANDOLPH SAMUEL RAE,

INVENTOR.

ATTORNEK Nov. 30, 1965 R. s. RAE

ENGINE Original Filed March 22. 1954 29 AM a 6 Sheets-Sheet 5 RANDOLPHSAMUEL RAE,

INVENTOR.

zen w A TTOR/VEV.

Nov. 30, 1965 R. s. RAE 3,220,183

ENGINE Original Filed March 22, 1954 6 Sheets-Sheet 4 RANDOLPH SAMUELRAE,

IN V EN TOR.

ATTORNEK N v- 3 1965 R. s. RAE 3,220,183

ENGINE Original Filed March 22, 1954 6 Sheets-Sheet 5 Q )1; ya 12/RANDOLPH SAMUEL RAE,

INVENTOR.

BY KSZLM M ATTORNEK R. S. RAE

Nov. 30, 1965 ENGINE 6 Sheets-Sheet 6 Original Filed March 22, 1954RANDOLPH SAMUEL RAE,

INVENTOR.

ATTORNEK United States Patent 3,220,183 ENGINE Randolph Samuel Rae, LosAngeles, Qalifi, assignor to The Garrett Qorporation, Los Angeles,Caliil, a corporation of California Original application Mar. 22, 1954,Ser. No. 417,867. Divided and this application Dec. 11, I961, Ser. No.

2 Claims. (Cl. oil-39.17)

This application is a division of application Serial No. 417,867, filedMarch 22, 1954 by Randolph Samuel Rae and entitled Non-Air BreathingEngine, now abandoned.

This invention relates to an engine capable of operating efficientlyindependently of the medium surrounding the engine and more particularlyto a prime mover for vehicles such as airplanes, rockets, submarines andtorpedoes, which will have the same order of eificiency as air breathingengines.

At very high altitudes and for underwater operation, there ispractically no air available for the combustion of fuel in an internalcombustion engine and therefore it is impossible for such an engine toproduce power economically. In the case of rockets, the propellantsupplies the needed oxygen but rocket engines have extremely lowefficiency. By the present invention, an engine is pro- Vided in whichthe oxidant is carried apart from the fuel and no great penalty is paidfor the weight of oxidant carried because of the high thermal efficiencyof the engine.

But for temperature limitations of the blades in a turbine, adequateamounts of the energy of a rocket fuel could be converted intomechanical work due to the fact that high pressure ratios could be used.This temperature limitation can be overcome by diluting the rocketgases. Hydrogen, due to its high specific heat value, about ten timesgreater than most gases, is the best material to use as a diluent.Further, as hydrogen is also one of the best fuels, it could be used forboth purposes. High pressure ratios can be used in the working cycle ofthis gas engine because both hydrogen and oxygen can be carried asliquid and therefore could be compressed to high pressure with but asmall expenditure of energy and without any appreciable increase intemperature.

By the use of several expansion stages in the engine, it is possible tolimit the temperature in each stage to that which can be withstood bythe materials now in use in practical engines. The efliciency obtainablefrom the engine of the present invention is of the same order as thatobtained from internal combustion engines at sea level and since theengine operates independently of its environment, this same efiiciencycan be obtained at very high altitudes or in other environments where itwould be impossible to operate the usual type of internal combustionengine to produce power economically. The type of prime mover utilizedfor each stage of the engine can be any type of fluid expansion engine,such as a gas engine or turbine, and therefore considerable flexibilityin the design of the engine is possible.

It is therefore an object of the present invention to provide an enginewhich is capable of operating efiiciently independently of the mediumsurrounding the vehicle so that the engine can be operated efficientlyin surrounding where practically no air is available.

Another object of the invention is to provide an engine for vehicleshaving the oxidant carried separately from the fuel and compressed tohigh pressures to provide a high efficiency in the working cycle.

A further object of the invention is to provide an engine comprised of anumber of stages so that the operating temperature of each stage can beheld to within the range of operating temperatures permitted by theconstruction materials.

"ice

Another object of the invention is to provide a non-air breathing enginewhose output is independent of the environment of the engine and whoseefficiency on the basis of fuel weight carried is of the same order asair breathing internal combustion engines operating at ground level.

These and other objects of the invention not specifically set forthabove will become readily apparent from the following description anddrawings in which:

FIGURE 1 is a diagrammatic view of a first form of the invention whereineach stage of the engine is supplied from a separate combustion chamber.

FIGURE 2 is a side elevational View of a physical form of the engineillustrated in FIGURE 1 showing a gas engine as the first stage andhelical flow turbines as the second and third stages.

FIGURE 3 is a top plan view of the engine, partly in section, takenalong line 33 of FIGURE 2 illustrating the manner in which the variousstages of the engine are connected together.

FIGURE 4 is a transverse vertical section along line 44 of FIGURE 3illustrating the construction of one of the helical flow turbines.

FIGURE 5 is a sectional view along line 5-5 of FIG- URE 4 showing one ofthe nozzles for the helical flow turbines.

FIGURE 6 is a vertical sectional view along line 66 of FIGURE 3illustrating the mounting of one of the turbine rotors.

FIGURE 7 is a vertical sectional view along line 7-7 of FIGURE 3illustrating one of the combustion chambers.

FIGURE 8 is a transverse sectional view along line 8-8 of FIGURE 7illustrating the flame holder contained within the combustion chamber.

FIGURE 9 is a diagrammatic view of a modification of the inventionwherein heat exchanges are positioned ahead of each of the stages of theengine.

FIGURE 10 is a side elevational View of a physical form of themodification illustrated in FIGURE 9.

FIGURE 11 is an end elevational view taken along line 1111 of FIGURE 10illustrating the arrangement of the heat exchangers.

FIGURE 12 is a vertical sectional view along line 12-12 of FIGURE 11showing the internal construction of one of the heat exchangers.

FIGURE 13 is a diagrammatic view of a second modification of theinvention wherein a single combustion chamber is used for all stages.

FIGURE 14 is a side elevational view of a physical form of the secondmodification of the invention showing the arrangement of the enginestages.

FIGURE 15 is a sectional view along line 15-45 of FIGURE 14 showing theheat exchange coils located within the heat exchange chamber.

Referring to the embodiment of the invention illustrated in FIGURE 1, afuel tank 16 is connected to heat exchanger 17 by means of a passage 18and the combustion chamber 19 is connected to heat exchanger 17 throughpassage 20 so that fuel leaving the tank 16 will be heated in the heatexchanger 17 prior to entering the combustion chamber 19. Any suitabletype of liquid or gaseous fuel can be utilized such as liquid hydrogen,gasoline, methane, acetylene, alcohol and the like, and the liquid orgaseous fuel can be compressed to a high pressure within tank 16 inorder to obtain a high efficiency in the working cycle of the engine. Aseparate tank 21 is utilized to carry the oxidant for the engine and thetank is connected to a heat exchanger 22 by a pasage 23. The combustionchamber 19 is connected to heat exchanger 22 by a passage 24 and apassage 25 containing valve 26 for regulating the amount of oxidantsupplied to the combustion chamber. Any

suitable type of oxidant, such as oxygen, hydrogen peroxide, nitricacid, etc., can be utilized in either the liquid or gaseous phase andcan be held under high pressure in tank 21 to increase the efliciency ofthe engine. When liquid fuel and oxidant are used, both will bevaporized before entering the combustion chamber by heat exchangers 17and 22, respectively, and the amount of oxidant will be controlled byvalve 26 so that the temperature of the gases leaving the combustionchamber will be the maximum that can be withstood by the constructionmaterials of the first stage. The combustion chamber 19 is connected bypassage 27 to the first stage 28 and the passage 27 will contain bothgaseous fuel and byproducts of the combustion reaction. For instance,when liquid hydrogen is utilized as the fuel, and liquid oxygen as theoxidant, the passage 27 will contain both hydrogen and steam resultingfrom combustion of part of the hydrogen, whereas, if a hydrocarbon isutilized as the fuel, the pas sage 27 will contain an amount ofhydrocarbon plus the various combustion products, such as carbondioxide, carbon monoxide and steam.

The first stage 23 of the engine will exhaust a lower temperaturethrough a passage 30 to a second combustion chamber 31 and a regulatedamount of oxidant will be led to the combustion chamber from passage 24through passage 32 and valve 33. In combustion chamber 31, some more ofthe fuel will be ignited with sufiicient oxidant to raise thetemperature in passage 34 to that which can be withstood by the secondstage 35 of the engine and the combustion in chamber 31 will reduce theamount of fuel and increase the produtcs of the combustion. The stage 35exhausts through passage 36 to a third combustion chamber 37 and theexpansion of the gases in stage 35 will result in a lower temperature inpassage 36. Additional oxidant is added to combustion chamber 37 frompassage 24 through passage38 and valve 39 and the amount of oxidant iscontrolled by the valve 39 so that the temperature in passage 40 leadingfrom the combustion chamber 37 will be raised until it is at thetemperature which can be withstood by the third stage 41 of the engine.The stage 41 exhausts to passage 42 which passes through the heatexchangers 22 and 17 and then to atmosphere in order to heat the oxidantentering heat exchanger 22 and the fuel entering heat exchanger 17.

It is understood that any number of stages can be added to the enginesuch as stage 43 having a combustion chamber 44 and that the oxygen canbe supplied to combustion chamber 44 from the passage 24. In general, apractical number of stages will be utilized so as to obtain a reasonablecompromise between the specific fuel consumption and the mechanicalcomplexity for the particular application under consideration. Thetemperature of the gases leaving the combustion chambers is regulated bythe amount of oxidant supplied to the combustion chambers through thevalves 26, 33, and 39. It is not necessary that the fuel and oxidant beat high pressure in tanks 16 and 21 respectively since pumps can beadded to passage 18 and 23 in order to increase the pressure in thesepassages leading to the heat exchangers 17 and 22, respectively. Also,it is understood that any one of the stages could consist of anysuitable type of power producing unit, such as a gas engine or turbineof any well known type. The engine of the present invention operatesindependently of the atmosphere since the engine carries its own fueland oxidant supply and each stage of the engine operates at the highestpossible temperature in order to obtain maximum efliciency from eachstage.

A physical embodiment of the invention is shown in FIGURE 2 wherein likereference numerals refer to like parts as in the diagrammatic view ofFIGURE 1. In this physical form, the first stage 45 of the invention iscomprised of gas expansion engine while the second and third stagesconsist of helical flow turbines 46 and 4-7 respectively, all of whichstages are connected to a common shaft 48. The common passage 24 isshown H- nected to combustion chambers 19, 31 and 37 through passages25, 32 and 38, respectively, which contain valves 26, 33 and 39 forcontrolling the amount of oxidant admitted to each of the combustionchambers. The combustion chamber 19 connects with engine 45 throughpassage 27, and the engine exhausts to combustion chamber 31 throughpassage 30. The combustion chamber 31 connects with manifold 49 ofturbine 46 through passage 34 and the manifold has two inlets 56 and 51.The turbine 46 exhausts through passage 36 to combustion chamber 37which is connected through passage 40 to intake manifold 52 having fourinlet passages 53, 53, 54 and 54 for turbine 47. The exhaust passage 42of the last stage turbine 47 passes through heat exchangers 22 and 17and then to atmosphere.

The gas engine 45 has a single, air-cooled cylinder 55 secured tocrankshaft casing 56 by screws 57 and a gear box 58 is secured to casing56 by screws 59. The engine crankshaft (not shown) is contained withincasing 56 and is connected to a gear train 60 located in gear box 58.The gear trains is connected to the common shaft 48 so that the outputof the engine is geared up to correspond with the speed of the turbines46 and 47. The helical fiow turbines 46 and 47 have a divided casingcomprised of casing sections 61 and 62 which are secured together bymeans of a number of screws 63 and the casing sections form bearingcontainer sections 64, 65 and 66, with one bearing section positioned onopposite sides of each turbine. Each of the bearing retainer sections iscomprised of a lubricating Well 67 formed in casing section 62 and acover member 68 formed in casing section 61 and having lubricatingopenings 69. A bearing support 70 is formed integral with cover 68 andretains a bearing 71 which supports the shaft 43. Each bearing has slits'72 and 73 on opposite sides of support member 70 for receivinglubricating rings '74 and 75, respectively, which are retained in theslits by a cover 71'. A portion of each of the rings is emerged in thelubricating fluid in space 67 in order to continually supply lubricantto the bearing during rotation of the rings by shaft 48. Each of thebearing retainer sections 64, 65, and 66 have sealing rings 76 and 77 atopposite sides of the sections in order to retain the lubricant. Thecasing sections 61 and 62 are also sealed against leakage of highpressure gases by members 78 and 79, each of which has three groovedspaces for receiving sealing rings 89, 81 and 82 and also a groove 83which exhausts to atmosphere.

Each of the turbines 46 and 47 has a rotor 84 which is secured to shaft48 by means of key 85 and is positioned along the shaft between nuts 36and 87 threaded to the shaft on opposite sides of the rotor hub. Eachrotor has a number of blades 88 continuous around the periphery of therotor and these blades define a number of reversing chambers or buckets89 which are semicircular. The inlet manifold 49 for turbine 46 has twobranches while the inlet manifold 52 for turbine 47 has four branchesand each branch of both manifolds leads to a nozzle 90 positioned at oneend of a reversing plate 91. Each plate 91 has curved flanges 92 and 93which are secured by means of rivets 94 to flanges 95 of proections 96carried by casing sections 61 and 62. The reversing plate 91 withflanges 92 and 93 are curved to conform to the outer periphery of theturbine rotor and each plate 91 has a number of sections 97 formingcavities 98 which are spaced to cooperate with the buckets 89 as theypass the reversing plate in order to give a swirling motion to thegases. The reversing plates are illustrated as having five cavitieswhich are continuously opposed to five of the buckets 89 and after eachbucket passes beyond the reversing plate, it is free to exhaust to theinside of the casing and then to either exhaust passage 36 or 42. Eachnozzle 99 is secured into the end of one of the inlet branches andpasses through the section 97 at the end of the reversing plate so thatthe gases enter the buckets 89 at one side thereof. It is understoodthat the gases,

swirling within the chambers defined by the buckets 89 and spaces 98,serve to rotate the turbine rotor and to drive the shaft 48.

The detailed construction of combustion chamber 37 is illustrated inFIGURE 7 and combustion chambers 19 and 31 are identical inconstruction. Four struts 100 within the chamber support a conicalsection 101 of flame holder 102 and the base of the section 101 supportsa wire mesh disc 103 on which is deposited finely divided platinum 104.The oxidant supply passage 38 projects into the combustion chamber andhas a nozzle end 105 which directs the oxidant against the finelydivided platinum so that the platinum acts as a catalyst to maintain theflame 106 during operation of the engine. Thus, continuous ignition of acertain portion of the fuel will take place at each combustion chamberand the amount of fuel ignited will depend upon the amount of oxidantpassing into each of the combustion chambers through the oxidant supplypassages. Other types of flame holders such as an electric spark plug,can be utilized in place of the finely divided platinum.

While the stages of the engine have been described as composed of a gasengine 45 and two helical flow turbines 46 and 47 it is understood thatany other suitable type of prime mover could be incorporated at anystage of the engine and that any number of stages could be utilized soas to obtain the maximum efficiency from the engine. The gas engine 45is of the usual well-known construction and the construction of thehelical flow turbines has been illustrated as one example of the type ofpower unit that can be used for any stage of the engine. The operationof the physical form of the invention will be the same as described inconnection with the diagrammatic form of FIGURE 1 wherein fuel issupplied to the first combustion chamber through heat exchanger 17 andoxidant is supplied to the first combustion chamber through heatexchanger 22. It is noted that the manifold for turbine 46 contains onlytwo inlets while the manifold for turbine 47 requires four inletsbecause of the expanded volume of gases passing through the turbine 47.The engine of this invention, comprises stages which operate at maximumefiiciency because the temperature at each of the stages is the maximumwhich can be used with available construction materials. The temperatureat the inlet of each of the stages is, of course, controlled by thevalves in the oxidant passages and the temperature at the inlet of eachstage can be varied by varing the supply of oxidant.

A first modification of the invention is diagrammatically illustrated inFIGURE 9 and in this modification, combustion chambers are connected toheat exchangers to raise the inlet temperature of each of the stages sothat the inlet temperature will be in the maximum which can be withstoodby the materials of each stage. As in the previous embodiment, thisembodiment has a fuel tank 16 for either liquid or gaseous fuel andoxidant tank 21, both of which can be under high pressure. The fuel isled through passage 109 to heat exchanger 110 and then by passage 111through heat exchanger 112 to passage 113 which connects with the firststage 114 of the engine. The fuel is heated in heat exchanger 110 andheat exchanger 112 serves to raise the temperature of the fuel whichpasses through the first stage 114 of the engine. Stage 114 exhaustthrough passage 115 to a heat exchanger 116 which leads through passage117 to the second stage 118 of the engine. The heat exchanger 116 servesto bring the temperature of the gaseous fuel up to that which can bewithstood by the second stage and this second stage exhausts throughpassage 119 to a heat exchanger 120 which connects through passage 121to the third stage 122 of the engine. The heat exchanger 120 serves toheat the temperature of the gaseous fuel up to that which can be 6withstood by the third stage of the engine. The third stage is connectedby exhaust passage 123 to the combustion chamber 124 where the firstcombustion of the fuel takes place. It is understood that any number ofstages can be utilized in the engine, such as stage 125 connected toheat exchanger 126 through passage 127.

The oxidant tank 21 connects through passage 128 to heat exchanger 129which in turn connects with oxidant supply passage 130. The branch pipe131 connects the passage through valve 132 to the combustion chamber 124so that a portion of the fuel can be ignited and the products leavingthe combustion chamber through line 133 pass through heat exchanger 120in order to raise the temperature of the fuel in line 121 to the desiredvalue for stage 122. The passage 134 connects heat exchanger 120 with asecond com bustion chamber 135 which is likewise connected to theoxidant passage 130' through passage 136 and valve 137. The oxidantsupply to combustion chamber 135 causes an additional portion of thefuel to be ignited and the products of combustion pass through passage136 to heat exchanger 116, where the gaseous fuel is raised to thetemperature suitable for stage 118. A passage 137 connects a thirdcombustion chamber 138 with the heat exchanger 116 and a passage 139containing valve 140 connects the combustion chamber 138 with theoxidant passage 130. In combustion chamber 138, additional fuel isignited and the combustion chamber is connected by passage 141 to heatexchanger 112 which serves to heat the gaseous fuel entering the firststage 114 to a temperature which is compatible with that stage. Theoutlet of heat exchanger 112 connects through passage 142 with heatexchanger 129 which serves to heat the oxidant which is supplied by line128 and heat exchanger 129 connects through passage 143 with heatexchanger 110 which serves to heat the fuel entering through passage109. The heat exchanger 118 then discharges to atmosphere throughpassage 144. The same types of fuels and oxidants can be utilized inthis modification as in the one previously described and instead ofhaving the fuel and oxidant under pressure in tanks 107 and 108, pumpscan be incorporated in passages 109 and 128 to increase the pressure offuel and oxidant respectively in order to obtain highest operatingefficiency. Also, it is understood that the various stages 114, 117 and122 can be any type of reciprocating engine or any type of turbine. Theamount of the fuel which is combusted in each of the combustion chambersis, of course, controlled by valves 132, 137 and 140 and the amount ofcombusted fuel will, of course, control the inlet temperatures to eachof the stages by determining the heat transfer at the heat exchangerbefore each stage.

A physical form of this second modification is illustrated in FIGURES 10through 12 wherein like reference numerals represent like parts as inthe previously described physical embodiment. The first stage of theengine is comprised of the gas engine 45 while the second and thirdstages are comprised of helical flow turbines 45 and 47 and all of thestages have a common drive shaft 48. The gas engine 45 is of the sameconstruction as the one previously disclosed and has an air-cooledcylinder 55 secured to a crankshaft casing 5-5 by means of screws 57.The casing 56 contains the crankshaft of the engine which connects withgears in gear box 58 in order to bring the speed of the engine up tothe. speed of the other stages. The turbine 46 of the second stage has amanifold 49 with branches 5% and 51 leading to the two nozzles of theturbine in the manner described in connection with the previousembodiment. Also, the turbine 47, comprising the third stage, has amanifold 52 with four branches 53, 54, 53' and 54 which lead to the fournozzles of this turbine in the same manner as in the previousembodiment. The turbines 46 and 47 are enclosed by casing sections 61and 62, which form on each side of the two turbines the lubricatingwells 64, 65 and 66, each comprised of a cavity 67 for the lubricant anda cover plate 68. The casing sections are screwed together by means ofscrews 63 and. are secured to the gear box 58 by means of screws 62.While the three stages of the engine are comprised of the samecomponents as in the previous physical embodiment, it is understood thatany type of fiuid engine can be utilized at any one of the stages, andthat the number of stages can be varied to obtain maximum operatingefiiciency.

The combustion chambers 124, 135 and 138 are of the same construction asused in the previous embodiment and illustrated in FIGURES 7 and 8. Theinlet to the engine 45 is heated to the desired temperature in the heatexchange 112 by the combustion gases from combustion chamber 138 and theengine 45 exhausts through heat exchanger 116 where the exhaust gasesare again heated to the desired temperature by the combustion gases fromchamber 135 passing through the heat exchanger. The

igh temperature gases from heat exchanger 116 pass through. manifold 49to the turbine 46 which exhausts to the heat exchanger 129 where theexhaust gases are again heated to the desired temperature by thecombustion gases from combustion chamber 124. It is apparent that thedriving fluid in all of the stages is pure gaseous fuel and that thefuel is not ignited in the combustion chambers until it has passedthrough all of the stages. FIGURE 12 illustrates the construction of theheat exchanger 121) and it is understood that the other heat exchangers112 and 116 are of like construction. The heat exchanger 120 has anouter circular casing 145 which has openings to receive inlet passage133 and exit passage 134. The passages 119 and 121 are continuousthrough the center of the casing 145 and this single passage has ahelical flange 146 positioned within the chamber 145 in order to providea large heat exchange surface for transferring heat to the gasesexhausting from turbine 46 and passing to turbine 47. This form of theinvention has the advantage that the driving fluid is pure gaseous fueland contains none of the products of combustion.

Another modification of the invention is illustrated in FIGURES 13through 15 wherein like reference numerals designate like parts as inthe previous embodiments. The diagrammatic form of the invention isshown in FIGURE 13 wherein fuel tank 16 is connected to heat exchanger147 through passage 148 and the heated fuel from heat exchanger 147passes through. line 148' and valve 149 to combustion chamber 150. Theoxidant in tank 21 is passed to heat exchanger 151 through passage 152and the outlet of the heat exchanger connects with combustion chamber151) through valve 153 and passage 154. The products of combustion fromchamber 150 enter one end of a large chamber 155 through passage 156 anda passage 157 connects the other end of chamber 155 with the first stage158 of the engine. The first stage 158 exhausts through passage 159 to afirst heat exchanger 161) located within the chamber 155. The outlet ofthe heat exchanger 160 connects to the second stage 161 through passage162 and the second stage exhausts through passage 163 to a second heatexchange 164, likewise located within chamber 155. The heat exchanger164 has an outlet leading to the third stage 165 through passage 166 andthe third stage exhausts through passage 167 to the heat exchangers 151and 147 connected by passage 168. The heat exchanger 147 has an outletpassage 169 leading to atmosphere. The fuel entering combustion chamber150 is supplied with sufiicient oxidant through passage 154 in order toprovide sufiicient heat energy to drive the three stages and the hightemperature combustion products pass into chamber 155 where thetemperature of these combustion products is decreased by the heat exchaners 160 and 164. Thus, the temperature of the exhaust from stage 158 isincreased by heat exchanger 160 to the temperature which can bewithstood at the inlet of the second stage 161 and the heat exchanger164 increases the temperature of the exhaust from the second stage 161to a temperature which can be withstood by the third stage 165. By thetime the combustion products enter the passage 157, leading to the firststage of the engine, the temperature of the products has beensufliciently reduced so that the temperature is that which the firststage can withstand. Thus, in the present modification, it is onlynecessary to utilize one combustion chamber and it is understood thatthe stages in the engine can take any desired form.

The physical embodiment of this second modification of the invention isillustrated in FIGURES 14 and 15 wherein like reference numeralsdesignate like parts as in the previous embodiment and the first stageof the engine is comprised of a gas engine 45 idential in constructionto that used in the other two forms. The gas engine 45 has an air cooledcylinder 55 which is secured to a crank shaft casing 56 by means ofscrews 57. A gear box 58 is secured to the casing 56 by means of screws59 and the gear box contains a gear train to increase the output speedof the gas engine to that corresponding to the other stages. The secondand third stages are com-prised of helical flow turbines 46 and 47,respectively, which are identical in form to those disclosed in theprevious embodiments. The turbines 46 and 47 have outer casing sections61 and 62 which are secured together by means of screws 63 and thecasing sections form bearing compartments 64, 65 and 66. All stages ofthe engine have a common shaft 48 which is supported by hearings in eachof the bearing compartments in the same manner as illustrated in thefirst embodiment. The passage 157 from chamber 155 leads to the firststage gas engine 45 and the passage 162 from the first heat exchanger160 leads to the manifold 49 of the second stage turbine 46. Themanifold 52 of the third stage turbine is connected to heat exchanger164 by passage 166. The heat exchangers 147 and 151 and combinationchamber can be of the same construction as the heat exchangers andcombustion chambers of the previous embodiments and it is understoodthat valves 149 and 153 regulate the combustion in chamber 150.Referring to FIGURE 15, the chamber is comprised of a cylindrical,divided casing 170 having the passages 156 and 157 connected to oppositeends thereof. The heat exchangers and 164 are both comprised of helicalcoils which have a series of cylindrical fins 171 in order to effect thetransfer of heat to the gases passing through the helical coils so thatthe temperature of the inlet gases to the second and third stages can beincreased by the combustion gases flowing through chamber 155. Due tothis transfer of heat, the gases leaving chamber 155 have been reducedto a temperature satis factory for the first stage 45 of the engine. Inthis modification of the invention, only a single combustion chamber isutilized and all the stages are driven by the same combustion products.

The present invention provides a non-air breathing engine which operatesefficiently independent of the surrounding medium and each modificationof the engine is divided into a sufficient number of stages to permitthe attainment of a low specific fuel consumption without having thetemperature at any one stage rise above that which can be withstood bypractical construction materials. In each modification, the shaft 48 candrive any suitable type of propelling device, either directly or throughgearing, and for high altitude flight, the propelling device can eitherbe a large propeller of high pitch or ducted fan and, of course, theusual underwater propeller can be used for propelling submarine craft.It is preferred to use liquid hydrogen as the fuel since it can becompressed to high pressures with a small expenditure of energy and alsohas a high specific heat. Also, liquid oxygen is preferred as theoxidant since it can likewise be compressed to high pressures in thestorage tank. It has also been determined that the engine of theinvention will have a specific fuel consumption of less than 1 pound offuel per horsepower hour, which compares favorably with the valuesobtainable by air-breathing internal combustion engines operating atground level.

In all forms of the invention, liquid hydrogen can be raised in tank 16to a high pressure with only a small expenditure of energy. The highpressure hydrogen enters the heat exchanger which receives the hightemperature engine exhaust and leaves this heat exchanger as hothydrogen gas at the pressure of the fluid in the tank. Similarly, aspreviously mentioned, a pump can be used to increase the pressure of theliquid hydrogen passing to the heat exchanger if the substance is storedas a low pressure liquid in tank 16. This again requires littleexpenditure of energy compared with what would have to be expended werethe hydrogen carried at atmospheric conditions of pressure andtemperature as a gas and raised to a corresponding pressure. If thepressure of the hydrogen upstream of the heat exchanger is above thecritical pressure, the hydrogen will of course be gaseous in form atthis point and the heat exchanger will serve to increase the temperatureof this gas. Thus, the design of the heat exchanger can be simplified inform. By using hydrogen gas as the diluent in each of the cycles, anexcellent working fluid is provided because of the high specific heat ofhydrogen. In other words, by using pure hydrogen gas as a working fluidin the stages and heat exchangers of all forms of the invention, moreenergy per pound of diluent or working fluid is available at any giventemperature than is available from most other known stable materials. Itis understood that the exhaust from all forms of the engine can containsome pure hydrogen gas so that hydrogen gas will be available in eachstage and in each heat exchanger of the various working cycles.

As previously pointed out, the various stages of the engine can be anysuitable type of turbine or gas engine. It is understood that thepreferred forms of the invention have been disclosed herein but thatother arrangements of combustion chambers and heat exchangers can beutilized to accomplish the combustion of the fuel without exceeding themaximum temperature which can be withstood by the engine constructionmaterial. Also, it is understood that the fuel tank and oxidant tank canbe insulated in any suitable manner to prevent evaporation of the liquidfuels and oxidants under high pressure. Various other modifications ofthe invention are contemplated by those skilled in the art withoutdeparting from the spirit and scope of the invention as hereinafterdefined by the appended claims.

What is claimed is:

1. An engine comprising separate fuel and oxidant supply means, saidengine being divided into a plurality of stages with the inlet to eachstage except the first connected to the preceding stage by conduit meanswhich passes through a heat exchanger through which the exhaust linefrom the final stage also passes in heat transfer relationship, passagemeans for connecting the inlet of said first stage to said fuel supplymeans through an additional heat exchanger in heat exchange relationshipwith said exhaust line downstream of the aforementioned heat exchangerso that uncom'bus-ted fuel passes through all stages for developingpower, a combustion chamber in the exhaust line from the last stageupstream of the heat exchanger for the last stage and separatecombustion chambers in the exhaust line upstream of the heat exchangerfor each stage so that said exhaust from the last stage passes seriallythrough the combustion chamber leading to the last stage heat exchanger,through the last stage heat exchanger and then successively through thecombustion chamber and heat exchanger for each preceding stage, andadditional conduit means for connecting each of said combustion chambersto said oxidant supply means for combusting a portion of said exhaust inorder to raise the inlet temperature for each stage.

2. The structure as set forth in claim 1 wherein there is provided, inaddition, two other heat exchangers through which the exhaust linepasses from said additional heat exchanger to the atmosphere, the firstsaid other heat exchanger being in said additional conduit means of theoxidant supply and the second being in the passage means of the fuelsupply upstream of said additional heat exchanger.

References Cited by the Examiner UNITED STATES PATENTS 730,248 6/1903Fr-iedenthal 36 1,988,456 1/1935 Lysholm -2 6073 2,268,270 12/ 1941Traupel 6039. 17 2,280,765 4/1942 Anxionnaz 6039.17 2,298,663 10/1942Traupel 60-73 2,346,179 4/ 1944 Meyer 6073 2,423,527 7/1947Steinschlaeger 60--39. 17 2,653,443 9/1953 Mercier 60-39. 17 2,795,1096/ 1957 Hryniszak 60-39.5 1 2,970,439 2/ 1961 Berl 60-3982 FOREIGNPATENTS 473,704 5/1951 Canada.

6,342 7/ 1907 Great Britain. 14,245 6/ 1906 Great Britain.

JULIUS E. WEST, Primary Examiner.

SAMUEL LEVINE, Examiner.

1. AN ENGINE COMPRISING SEPARATE FUEL AND OXIDANT SUPPLY MEANS, SAIDENGINE BEING DIVIDED INTO A PLURALITY OF STAGES WITH THE INLET TO EACHSTAGE EXCEPT THE FIRST CONNECTED TO THE PRECEDING STAGE BY CONDUIT MEANSWHICH PASSES THROUGH A HEAT EXCHANGER THROUGH WHICH THE EXHAUST LINEFROM THE FINAL STAGE ALSO PASSES IN HEAT TRANSFER RELATIONSHIP, PASSAGEMEANS FOR CONNECTING THE INLET OF SAID FIRST STAGE TO SAID FUEL SUPPLYMEANS THROUGH AN ADDITIONAL HEAT EXCHANGER IN HEAT EXCHANGE RELATIONSHIPWITH SAID EXHAUST LINE DOWNSTRAM OF THE AFOREMENTIONED HEAT EXCHANGER SOTHAT UNCOMBUSTED FUEL PASSES THROUGH ALL STAGES FOR DEVELOPING POWER, ACOMBUSTION CHAMBER IN THE EXHAUST LINE FROM THE LAST STAGE UPSTREAM OFTHE HEAT EXCHANGER FOR THE LAST STAGE AND SEPARATE COMBUSTION CHAMBERSIN THE EXHAUST LINE UPSTREAM OF THE HEAT EXCHANGER FOR EACH STAGE SOTHAT SAID EXHAUST FROM THE LAST STAGE PASSES SERIALLY THROUGH THECOMBUSTION CHAMBER LEADING TO THE LAST STAGE HEAT EXCHANGER, THROUGH THELAST STAGE HEAT EXCHANGER AND THEN SUCCESSIVELY THROUGH THE COMBUSTIONCHAMBER AND HEAT EXCHANGER FOR EACH PRECEDING STAGE, AND ADDITIONALCONDUIT MEAND FOR CONNECTING SAID OF SAID COMBUSTION CHAMBERS TO SAIDOXIDANT SUPPLY MEANS FOR COMBUSTING A PORTION OF SAID EXHAUST INORDER TORAISE THE INLET TEMPERATURE FOR EACH STAGE.